TWI338452B - Charge pump - Google Patents

Description

1338452 FIELD OF THE INVENTION The present invention relates to a charge pump with immediate current calibration, and more particularly to a charge pump that utilizes an adjustable current source to compensate for current mismatch. [Prior Art]

Figure 1 is an embodiment of a charge pump circuit of a conventional phase lock loop (PLL) or a delta ay locked loop (DLL). As shown in the figure, the charge pump 1 〇 includes two current sources 11, 12, switches 13 controlled by control signals UP, DN, 132, 133, 134, and an operational amplifier (〇p ) l4. When the upper and lower current sources 11 and 1 2 are not matched, the mismatch will cause the voltage of the voltage controlled oscillator (VCO) to be disturbed, which may cause phase noise or/and jitter of the output signal ( Jitter) becomes bigger. Figure 2 is another embodiment of a charge pump circuit of a conventional phase lock loop (PLL). As shown in the figure, the charge pump 20 includes two digital analog converters (DACs) 2, 22, switches 131' 132 133, 134 controlled by control signals UP, DN, and an operational amplifier (OP) 14 . However, this method has the following disadvantages: 1. Due to the limitation of the resolution of the DAC. When the calibration is completed, there are still slight errors in the two currents Id and Idn. Second, this method must be off line for calibration. And when the calibration is completed, the two currents Iup, Idn occur for some reason (such as temperature change). 6 1338452 Mismatch will reduce the calibration effect. Another-known charge pump is disclosed in US Patent No. 6,326,852. ^ A conventional charge pump has a relatively complicated circuit and a high power consumption / ~ SUMMARY OF THE INVENTION In view of the above problems, it is an object of the present invention to provide a charge pump with current calibration to overcome the above problems. One of the objects of the present invention is to provide a charge pump with current calibration that instantly adjusts the current to match. One of the objects of the present invention is to provide a charge pump with current calibration to overcome current variations due to changes in ambient temperature. To achieve the above object, the charge pump of the present invention comprises: a tunable current source package s a first current source and an impedance unit and provides an adjustable current; a second current source provides a second current; a switching unit and a second switching unit are coupled between the adjustable current source and the second current source; and a control circuit for controlling the current amount of the adjustable current source to enable the adjustable current The current is substantially equal to the second current. Therefore, even if the current of the first current source does not match the current of the second current source, the current of the adjustable current can be substantially equal to the second current by the control circuit. [Embodiment] Fig. 3 is a circuit diagram of a charge pump of the present invention. As shown in the figure, the charge pump 30 with immediate current calibration includes two current sources 3 1 and 32, and the switch controlled by 1338452 to control the k number UP! 3 1,! 32. A switch 133, 134 controlled by a control signal DN, and a capacitor n C1. In one embodiment, the first current source 3 1 includes a first current source 3 u and an impedance unit Zup. In another embodiment, the second current source 32 includes a second current source 321 and a blocking unit 7C ZDN. . The first current source 3! is connected to the first end of the switch t3丨, 丨32; and the second current source 32 is connected to the first end of the switch 丨33, 丨34. The second end of the switch 131 is connected to the second end of the switch 133 and forms a first current path, and the second end of the switch 132 is connected to the second end of the switch 134, and f forms a second current path. The capacitor C1 is connected to the first current path to be charged and discharged via the first current path, and the current output terminal is connected to the second current path to provide an output current “ut. When the PLL is locked, the two current sources of the charge pump 3〇 3丨, 32 will be periodically switched to the first current path or the second current path by the switches 131, 132, 133, 134. Equation (1) can derive the voltage change of the capacitor C1.

I = c

dV

When there is a mismatch between IUP and IDN, current will flow in and cause vc to change. Therefore, if the system maintains a fixed voltage by adjusting / or ZDN,

If the current flows out of the capacitor C1, the whole impedance unit ZUP cancels the mismatch between the current Iup and the IDN. Of course, one of the two impedance units hp, zDN can be omitted. Of course, both current sources 31, 32 benefit = are adjustable. The impedance unit can be implemented by a -variable resistor, a resistor network, a transistor in series with a resistor, or by other conventionally constructed impedance units. 1338452 Figure 4A is a first embodiment of a charge pump having a feedback mechanism of the present invention. As shown in the figure, the charge pump 40 includes an adjustable current source 41 to provide a current IUP and a second current source 42 to provide a current Idn 'switches 13 1 , 132 controlled by a control signal UP, controlled by a control signal DN The switches 133, 134, a capacitor C1, and a control unit 杓. The control unit 43 can be an operational amplifier 431. The current source 41 includes a first current source 411 and an impedance unit 412. The impedance unit 412 receives the output signal of the operational amplifier 431. Therefore, the current flowing through the impedance unit 4 1 2 is controlled by the output voltage of the operational amplifier 431. The positive input terminal of the operational amplifier 5| 4 3 1 is connected to the capacitor C1, the negative input terminal is connected to a voltage Vdc, and the output terminal is connected to the impedance unit 412. When the currents IUP and IDN do not match, the voltage vc of the capacitor C1 changes. The operational amplifier 43 1 controls the current flowing through the impedance unit 412 at any time in accordance with the voltage Vc to match the currents iup and Idn. For example, when the current Iup is less than the current Ι〇ν, the electric cell C1 will discharge, causing the voltage vc to decrease. At this time, the output voltage of the operational amplifier 43 1 also decreases, so that the current flowing through the impedance unit 4 1 2 increases. vice versa. Therefore, the charge pump of the present invention can instantly calibrate the magnitude of the current IUP' Idn to match. Figure 4B is a second embodiment of the charge pump of the present invention. The charge pump 40' of this embodiment is almost identical in architecture to the charge pump 4' of the first embodiment except that the negative input of the operational amplifier 431 of the charge pump 40' is directly connected to the second current path. That is, the output voltage Vcut is replaced by the charge pump 4A in place of the voltage vdc. Although the charge pump 4 of the first embodiment and the operational amplifier 431 of the charge pump 1338452 of the second embodiment are used to regulate the current of the source 4, if the second power = the first - adjustable The current is also used by the operational amplifier to call the adjustable current source, which is just below the adjustable current. Referring to Figure 4C, a third embodiment of the charge pump of the present invention will no longer be described herein; Another embodiment is the current sources 4 i and 42. The operational amplifier 431 can also be adjusted at the same time, and the current source can be adjusted. Adjustable current source above and below

Fig. 4D is another embodiment of the adjustable current source of the charge fruit of the present invention. The tunable current source 41 includes two transistors 411, 412, and a resistor R412'', that is, a transistor 412, in series with a resistor R4u, in place of the impedance unit 412. SUb, transistor 4U, and resistor R412 are designed to be very flexible. Figure 5 is a fourth embodiment of the charge pump of the present invention. As shown in the figure, the charge pump 50 includes two current sources, two switch modules 5, 52, and a capacitor C1. The two current sources are implemented by two transistors sharing the output stage of a 〇p amplifier 53. In one embodiment, even a circuit of current mismatch correction and charge sharing removal can be implemented together. In a preferred embodiment, for stability problems and prevention of current switching during switching, the 〇p amplifier 53 is an open loop, and some low-pass filters 54, such as a resistor R2 and a capacitor C2 network, may be added. The input of the OP amplifier 53 is fixed, and the control currents IUP and IDN are fixed. Figure 6 is a fifth embodiment of the charge pump of the present invention. As shown in the figure, the charge pump 60 with immediate current calibration includes two current sources 61,

10 1338452 Causes the current of the current source to change the current ιυρ, iDN. Therefore, the charge pump of the present invention is adjusted to match at any time even if the ambient temperature changes. However, the invention is not limited thereto, and various modifications may be made without departing from the spirit and scope of the invention. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is an embodiment of a charge pump circuit of a conventional phase-locked loop. Fig. 2 is another embodiment of a charge pump circuit of a conventional phase-locked loop. Fig. 3 is a circuit diagram of a charge pump of the present invention. Fig. 4A is a first embodiment of the charge pump of the present invention. Figure 4B is a second embodiment of the charge pump of the present invention. Figure 4C is a third embodiment of the charge pump of the present invention. Figure 4D is an alternative embodiment of the current source of the charge pump of the present invention. Figure 5 is a fourth embodiment of the charge accumulation of the present invention. Figure 6 is a fifth embodiment of the charge pump of the present invention. Figure 7 is an embodiment of an edge comparator of the present invention. Figure number 1 () '20 charge pump 11 ' 1 2 current source 131 , 132 , 133 , 134 switch 12 1338452 14 , 43 operational amplifier 21 , 22 digital analog converter 30 , 40 , 40 ' , 40 " , 50 , 60 Instant current calibration charge pump 31, 32, 61, 62, 61 1 Current source 4 1 , 4 1 ', 4 1 1 , 4 1 2, 4 1 2', 42, 42 1 , 422 Current source 43 Control circuit 51, 52 switch module 53 OP amplifier 54 low pass filter 612 adjustable current source 62 control circuit 63 edge comparator 64 smoothing unit Cl, C2 capacitor

Rup, Rdn, R2 resistor

Claims (1)

1338452 0 years 丨) month | Japanese revision, patent application scope: 1. A charge pump, comprising: an adjustable current source, comprising a first current source, and used to provide a first current; a current source is provided with a second current; a first switching unit is controlled by a first control signal to connect the first current source to a first current path or a second current path; a second switching unit, Controlling, by a second control signal, the second current source to the first current path or the second current path; a first capacitor coupled to the first current path and not coupled to the second current path; and a control circuit directly controlling the adjustable current source according to the capacitor voltage change of the first current path, such that the The first current is substantially equal to the aforementioned second current, wherein the charge pump does not include other current sources having a mirror relationship with the first current source or the second current source. 2. The charge pump of claim 1, wherein the adjustable current source comprises a first impedance unit, and the first impedance unit is a resistor network. 3. The charge pump of claim 1, wherein the adjustable current source comprises a first impedance unit, and the first impedance unit is a variable resistor. 4. The charge pump of claim 1, wherein the adjustable current source comprises a first impedance unit, and the first impedance unit is a transistor and a resistor connected in series. 5. The charge pump of claim 1, wherein the adjustable current source comprises a first impedance unit, and the first impedance unit is a transistor. 14 1338452 6. = Please refer to the charge pump described in Item 2, 3, 4 or 5 of the patent scope, where::::Electrical: is a different amplifier, the positive input of the operational amplifier receives the voltage and negative of ^ The input terminal inputs a constant voltage, and the output terminal 7 controls the current source to control the first current of the adjustable current source. The charge pump according to claim 1, wherein the charge pump further includes a second impedance unit 70'. The second impedance unit is connected in parallel with the second current source. 8. The charge pump as described in the scope of the patent application, wherein the first and the second 9 The source system is one of the first-transistor and the second transistor. .4 of the invention of claim 8 wherein the output stage is located within the control circuit. A charge pump comprising: a first current source providing a first current; a second current source providing a second current; - a first switch unit being controlled by a first control signal Connecting the first current source to a first current path or a second current path; ', a second switching unit is configured to control the second current source to be connected to the first current path or the second current path by using a second control signal; the control circuit is configured to receive the first and second Controlling the money and controlling the amount of current of the first current according to the first and the second control signal such that the first electrical quantity is equal to the second current; and wherein the control circuit comprises: - an edge comparator Receiving the first and second control signals and comparing the first control signal and the second control signal to generate an edge signal; and - smoothing the single s, after receiving the edge signal, generating - controlling, and utilizing The control signal controls the first. The current described in the item. For the - low pass wave. What is the power of the system? The smoothing unit 2, such as _ patent pending the ω item, is the RC circuit. The electric power is loaded, and the smoothing unit is shot. 3. If the scope of the patent application is -, the phase is - phase _. Edge comparator 14. The charge pump described in item 10, wherein the edge comparator is a horse-frequency phase comparator. As stated in the first paragraph of the patent scope, f 2 φ β Ρ is a 1-lock circuit. , the edge comparator 6 · a charge pump, comprising: a first current source, providing a first current; a second current source providing a second current; ~~ the first current path The method includes: 1 - a switch between the -th node and the second current source; and a second switch 'between the first node and the first current source; - a second current path, including : = the third switch is located between the second node and the second current source; and the second and fourth switches are located between the second node and the first current source; the second 4 4th - and $ The second open relationship is controlled by the __th control signal, and the fourth open relationship is controlled by a second control signal; the heart control circuit receives the first and the second control signal, and according to The first and fourth control signals are used to control the current amount of the second current, such that the first current is 1338452 which is qualitatively equal to the second current; wherein the charge pump does not include the first current source or the second The current source has a mirror relationship His current source. 17. The charge pump of claim 16, wherein the control circuit comprises: an edge comparator for comparing the first control signal and the second control signal to generate an edge signal; and a smoothing The unit receives the edge signal to generate a current control signal, and uses the current control signal to control the current of the second current source. 18. The charge pump of claim 17, wherein the smoothing unit is a low pass chopper. 19. The charge pump of claim 17, wherein the smoothing unit is an RC circuit. 20. The charge pump of claim 17, wherein the edge comparator is a phase detector. 21. The charge pump of claim 17, wherein the edge comparator is a frequency phase comparator. 22. The charge pump of claim 17, wherein the edge comparator is a latch circuit. 23. The charge pump as described in claim 16 is located in a phase-locked loop (PLL). 24. The charge pump as described in claim 16 is located in a delay locked loop (DLL). 25. A charge pump comprising: a first current source providing a first current; 17 1338452 - a second current, - a second current source 'for controlling current according to - current to provide wherein the second current is substantially Equal to the first current; a first current path comprising: between the point and the second current source; and between the node and the first current source; a first switch located in a first to a second a switch, located in the first second current path, comprising: - a third switch 'between - the second node and the second current source, and a fourth switch 'between the second node and the first current source; and a control circuit for receiving and comparing the voltage of the first node and the -fixed voltage to output the current control signal; The charge pump does not include other current sources having a mirror relationship with the first current source or the second current source. 26. The charge pump of claim 25, wherein the second current source comprises: - a fixed current source to provide a fixed current; An adjustable current source for providing a regulated current based on the current control signal. A charge pump as claimed in claim 25 of the patent scope, the adjustable current source comprising: - a first transistor; - a resistor connected in series with the first transistor. 28. The charge pump of claim 27, wherein the resistor changes the resistance according to the current control signal. 29. The charge pump as described in claim 27 is located in a phase-locked loop. 1338452 30. The charge pump as described in claim 27 is located in a delay locked loop. 31. A charge pump comprising: an adjustable current source comprising a first current source for providing a first current; a second current source for providing a second current; a first switching unit, Controlling the first current source to a first current path or a second current path by a first control signal; a second switching unit controlling the second current source by a second control signal Connected to the first current path or the second current path; a first capacitor coupled to the first current path and not coupled to the second current path; and a control circuit directly based on the first current path The capacitor voltage is varied to control the adjustable current source such that the first current is substantially equal to the second current; wherein the control circuit is an operational amplifier, and the positive input terminal of the operational amplifier receives the voltage of the first capacitor, A negative input inputs a fixed voltage, and an output is coupled to the adjustable current source to control the first current of the adjustable current source. The charge pump of claim 31, wherein the adjustable current source comprises a first impedance unit, and the first impedance unit is a resistor network. 33. The charge pump of claim 31, wherein the adjustable current source comprises a first impedance unit, and the first impedance unit is a variable resistor. 34. The charge pump of claim 31, wherein the adjustable current source comprises a first impedance unit, and the first impedance unit is a transistor in series with a resistor. 19 includes the charge pump described in the item, wherein the adjustable current source 36 Γ is an impedance unit, and the first impedance unit is a transistor. Please, as described in item 31 of the profit range, further includes a second impedance 兀 first impedance 711 is connected in parallel with the second current source. = === The charge pump described in item 2, wherein the first and the first body source are the same as the first transistor and the second transistor 38. Range 37 is within the control circuit. Recorded charge dish' where the output level is 20